Tack cloth coated with plasticized synthetic resin and method for preparing same



United States Patent 3,208,093 TACK CLOTH COATED WITH PLASTICIZED SYN- THETIC RESIN AND METHGD FOR PREPARENG SAME Webster H. Hansen, Monrovia, Califi, assiguor to Fred M. Greider, Pasadena, Qalif. No Drawing. Fiied May 31, 1960, Ser. No. 32,526 14 Claims. (Ci. 155i}6) This invention relates to tack cloths and more particularly to an improved article of such kind and to a tackifier composition and method for impregnating a backing material or fibrous web to provide a product having many properties and characteristics not possessed by previous products of this type.

This is a continuation-in-part of my copending application Serial No. 816,717, filed May 29, 1959, now abancloned.

Tack cloths are used in large number by surface finishers as well as in the home to remove dust and fine particles of foreign matter either as an incident to the application of surface finishes or to maintain the finished surfaces clean. Particularly large users of such cloths are the automobile manufacturers and refinishers as well as in dustrial enamelers who are confronted with the problems of applying coatings forming high luster flawless finishes over large areas of items in mass production. Despite efforts to conduct the finishing operations in closed areas maintained clean by high efficiency filters and air conditioning systems, tack cloths must be employed constantly and repeatedly to remove and hold captive every possible particle of foreign matter.

Tack cloths as heretofore provided for this purpose are subject to numerous disadvantages and shortcomings sought to be avoided by the present invention. Among the many undesirable characteristics of previous tack cloths heretofore assumed to be inherent in a cloth capable of performing satisfactorily its essential functions has been the stickiness or gumminess of the tackifier or active agent with which such cloths are impregnated. While these properties have been deemed both desirable and necessary to capture foreign matter, this very property was inseparable from the pronounced tendency of the tackifier to transfer to other surfaces including the surface sought to be cleaned, thereby substituting one surface contaminant for another. Prior tackifiers als transfer readily to the operators hand and from his hand to other objects contacted by the hand. In consequence, tack cloth operators are required to use every precaution not to permit their hands to come in contact with the surfaces being cleaned.

These same sticky characteristics of prior cloths also have necessitated the packaging of cloths for storage and transit in special wrappers and packaging materials for various reasons. Additionally, some of the tackifying compositions contain fugitive ingredients or solvents which vaporize if the cloths are not packaged in sealed wrappers. Special packaging has also been necessary to prevent c0ntamination of both the cloths and the shipping containers.

Other undesirable characteristics of prior tack cloth products include their sensitivity to temperature changes and the narrow temperature ranges within which they can be used elfectively. At low temperatures the cloths ecame stiff, harsh and ineffective to pick up and retain foreign matter. At higher temperatures the prior tackifier is too sticky and transfers far too readily to objects in contact therewith. Another serious disadvantage of many prior cloths has been their pronounced flammability. Even more serious has been the liability of certain types of tack cloths, particularly when dirty or contaminated, to burst into flame from spontaneous combustion.

'ice

In the light of the foregoing disadvantages and undesirable characteristics of prior tack cloth products, it is the object of the present invention to provide a tackifier composition and a tack cloth prepared therefrom which avoids each of the aforementioned and other undesirable characteristics. The compounded treating material of this invention is formulated from plastic resin conditioned by suitable plasticizers and other modifiers as to provide a resulting composition particularly characterized by its lack of stickiness and gumminess to the touch, and more particularly, one which is highly resistant to transfer from the tack cloth fabric to either the operators hand or to the other surfaces, and yet which is remarkably effective and efiicient in picking up and holding captive, dust and other foreign matter. The described properties are exhibited over a wide temperature range extending both below and above work room temperatures during both winter and summer months, thereby avoiding changes in the efiiciency of the cloth under different temperatures and obviating the need for either the heating or the cooling of the working space. The present tackifier is free from objectionable odor and is water white in color, a most desirable characteristic not possessed by prior tackifiers. Owing to its property of not transferring tackiness and stickiness to contacted articles, as well as to the highly stable character of the invention composition, no special packaging is required and separate cloths may be folded and packed in direct contact with one another in cardboard or other inexpensive and unprotected packaging materials for prolonged storage without adverse effects or deterioration in any respect.

Still another especially important feature of the present invention is the fact that the tackifier ingredients are dispersible in an aqueous vehicle while being compounded and distributed over the fabric of the tack cloth. This feature contrasts sharply with prior products which have required other vehicles and solvents having highly objectionable properties. Not only is the water vehicle use in preparing the present invention inexpensive, but it is subject to none of the many objections and hazards of the vehicles and solvents previously proposed. Not the least of these has been the inescapable fire hazard of certain prior vehicles. Furthermore, the tackifier ingredients of this invention are not redispersible in water after evaporation of the latter from the tack cloth during the manufacture of the cloth.

Of particular importance is the fact that the tack cloth product of this invention is non-flammable and thus is not subject to spontaneous combustion before or after use. Furthermore, the cloth may be used with equally effective results by both the novice and the skilled workman. Still another new and important property of the present invention is the pronounced ability of the compound to engulf foreign matter in contact therewith. Accordingly, the tack cloth constantly tends to rejuvenate and to surround adhering particles with a fresh surface tackifier.

Accordingly, it is a primary object of the present invention to provide an improved tackifier com osition and a fabric product or backing material impregnated therewith, each having highly superior properties to prior products developed for the purposes referred to herein.

Another object of the invention is the provision of a tackifier composition having an initially minutely dis crete, polymeric resinous base transistorily dispersible in Water to facilitate the impregnation of cheesecloth and the like fabric therewith, which composition after solvent removal and coalescence of particles upon the supporting fabric, remains highly effective and efficient over a wide temperature range and is characterized in particular by its ability to capture and retain foreign material without tending to transfer to surfaces contacted thereby.

Another object of this invention is the provision of a tackifier composition prepared with a water vehicle which vaporizes following the impregnation of the tack cloth with the composition and which adhered composition thereafter remains non-soluble in water, thereby providing a product not subject to change after manufacture due to losses or gains by evaporation or absorption of the vehicle.

Another object of the invention is the provision of a tackifier composition having a resinous emulsion base suitably modified by a selected pair of plasticizers, which may be fire retardant and capable of being temporarily dispersed in water as a vehicle for application to a fabric and rapid withdrawal of the aqueous dispersant.

Another object of the invention is the provision of an improved tack cloth impregnated with a tackifier composition deposited from a transitory aqueous dispersion or emulsion and which applied composition is characterized by being substantially white in color, non-flammable, non-volatile, and not subject to spontaneous combustion.

Another object of the invention i the provision of a tack cloth impregnated with a finely-divided, resin base tackifier complex marked rejuvenation properties by reason of its tendency to engulf foreign matter brought in contact therewith. In this connection it is important to note that the particles of resin-plasticizer coalesce very appreciably after deposition upon the backing material from the temporary emulsion (though not forming a continuous film as is the case with glazed paper), their unique property which may be designated non-adhesive tackiness apparently being the result of incorporation of the plasticizers with the resinous plastic while the latter is in the form of minute particles.

The tack cloth impregnating composition of this invention comprises an aqueous dispersion or emulsion of a polymeric resin, a pair of plasticizers for imparting a unique tackiness to the solid complex, and optionally a temporary emulsifying agent, preferably of the non-ionic type.

The present invention is based in part upon the observation that intimate mixtures of finely divided resinous polymer with a matching pair of plasticizers, as herein defined, provide a composition substantially permanently tacky which can advantageously be used to impregnate or be deposited upon fibrous webbing or more or less flexible supporting sheet material so as to produce what is commonly known as a tack rag or tack cloth possessing improved properties, more particularly, a non-adhesiveness of the tacky substance. For ease in application to such backing material, whether discontinuous (e.g., excelsior), spongy or in sheet form, the composition may be dispersed as an emulsion in aqueous media in order to allow the absorbent backing material to be dipped or soaked therein. However, a more viscous form of the composition can be applied to sheet material by brushing, or it can be sprayed upon any form of the backing material when of suitable viscosity for use in sprayers. Or in the case of sheet material, it can be rolled on. For forming an aqueous dispersion of the resin-plasticizer complex, a non-ionic emulsifier or surface active agent is employed since a long-lasting or permanent emulsion is not desired, the aqueous phase being removed relatively quickly from the backing material by evaporation, either naturally occurring or conveniently accelerated by the application of heat and/ or vacuum. Indeed, in some instances the emulsifier may be totally omitted, particularly when starting with an emulsion of the polymer of the required particle size. The resinous polymer is desirably on the order of 0.1 to 0.2 micron size, at least a major portion being particles of this size and at least 80% or 90% being less than micron at the time of dispersal with the plasticizers.

The polymer is desirably of such character as to be solid at normal temperature of about 20 C. The emulsified suspension is obtained by homopolymerization or copolymerization of any polymerizable olefinic compound, especially those containing a vinylidine group (CH =C The polymerizable compounds which form resinous polymer by addition polymerization involving carbon-to-carbon bonding through olefinic carbon atoms include vinyl halides like vinyl chloride or bromide; vinyl esters such as vinyl acetate, propionate or butyrate; vinylidene chloride or bromide; vinyl aromatic compounds like styrene, methyl styrene and chlorostyrene; acrylate and methacrylate esters like methyl, ethyl or butyl acrylate or methacrylate; unsaturated nitriles such as acrylonitrile and methacrylonitrile; vinyl ketones such as methyl vinyl or methyl isopropenyl ketone; allyl compounds such as allyl chloride as well as similar singly olefinic compounds. Also suitable are compounds which contain a plurality of olefinic linkages between aliphatic carbon atoms that are adapted to enable formation of addition polymers as is the case with butadiene-1,3, isopropene, 2,3-dimethyl butadiene-1,3, chloroprene, divinyl benzene, 2-methyl pentadiene-2,4, 2-methyl pentadienel,3, ethylene glycol dimethacrylate, diallyl phthalate, diallyl diglycolate, allyl vinyl phthalate, diallyl maleate, diallyl fumarate, diallyl ether of ethylene glycol, triallyl ether of glycerol, and similar compounds as well as their homologs. Copolymers can be prepared by use of mixtures of one or more of the polymerizable compounds, the mixture containing at least an appreciable proportion of any one of the compounds, i.e., at least 1% of a second, third or fourth compound. For example, vinyl chloride can be mixed with 5% to 25% of vinyl acetate, and, if desired, 1% to 5% of divinyl benzene can be present as third constituent.

Aqueous suspensions of emulsified polymer may con tain any desired concentration of polymer. Ordinarily, it is preferred to employ concentrated mixtures containing about 30% to 60% polymer, although more dilute mixtures may be employed if desired. Of these, p0ly= vinyl acetate is particularly suitable for economic reasons and because of the ease with which it can be plasticiZecl to provide a highly superior and stable tackifier, plus the stability of its tacky condition over a wide temperature range. In many instances, resinous polymers of the designated particle size are commercially available as aqueous emulsions referred to as a latex of the polymer.

Plasticizers found particularly suitable for rendering the above mentioned resinous emulsions tacky and nontransferable from impregnated fabric to other surfaces are the normally liquid phosphate and phthalate plasticizers, one of each class being selected. They include: tricresyl and triphenyl phosphates, dibutyl, tributyl, tri= butoxyethyl, di-isodecyl, di-hydroxyethyl, hexyl and oth= er alkyl phosphate esters. The phosphate plasticizing modifiers have marked fire retardant properties highly desirable in a satisfactory tackifier composition. Suitable phthalate plasticizers include dibutyl phthalate, diethyl phthalate, di-isobutyl phthalate, di-isoctyl phthalate, di (2 ethyl hexyl) phthalate, dinonyl phthalate, didecyl phthalate, dimethyl sebacate, dibutyl sebacate, dihexyl sebacate, dibutyl adipate, and di-isooctyl adipate. The total amount of plasticizer should be a minimum of about of the quantity of resin (by weight) preferably a minimum of about to While tacky properties which often result from various combinations of the present resins and plasticizers have often been studied and sundry methods have been suggested to overcome or utilize this characteristic, generally these diverse suggestions have met with only limited success. Thus various formulations have employed plasticized resins in part as adhesives or in other surface coatings such as slow drying paint. However, small changes in formulations often produced unanticipated (and undesirable) products. Likewise, methods for permanently stabilizing aqueous dispersions of such resins and plasticizers have been suggested, but their purpose is obviously the opposite from the present object of preparing tack rags by depositing the resin-plasticizer complex on suitable backing material in What desirably becomes a solvent-free form as soon as possible. For the present purpose, if an aqueous dispersant is employed from which to deposit the tacky complex on the backing material, it should be only transitorily or temporarily present so as to be readily or quickly separable from the final product; in particular, the use of emulsifiers which create or stabilize a permanent suspension or jelly of the resinplasticizer complex is to be avoided. Thus, without Wishing to be committed to an exact theory of reaction, it seems essential for the present non-adhesive tackiness that (though the plasticized polymer particles coalesce during and after deposition on the backing material) the plasticizers should remain in most part dispersed about (obviously in the solid state adhering to) the minute polymer particles of 0.1 to 0.2 micron. Accordingly, it is important that dispersal or suspension of the polymerplasticizer mixture (or plasticized polymer") whether or not in the form of a true emulsion, be readily broken down upon its application to the fibrous backing material. Thus it is desirable that the fibrous backing material, for example, sheets of cheesecloth, be able to dry in fairly short time after being removed from the fluid composition and hung up in a current of air, heated if convenient.

Any suitable non-ionic emulsifier or surface active agent may be employed with the above enumerated in gredients, a particularly satisfactory emulsifier being nonyl phenyl polyethylene glycol ether employed in all examples below (trade name Tergitol).

In the following illustrative examples, in each case the polymer had a particle size on the order of 0.1 to 0.2 micron.

A preferred composition A preferred specific example of a tackifier composition exhibiting the features of this invention comprises the following ingredients in the indicated parts by weight:

Second preferred specific composition A second specific composition comprises the following ingredients in the indicated parts by weight:

Preferred Permissible Ingredient quantity, quantity parts range Acrylic Polymer emulsion (chiefly 130 110 to 150 parts.

methyl methacrylate).

2-ethyl hexyl diphenyl phosphate 75 50 to 70 parts. Butyl benzyl phthalate l 5 to 25 parts. Non-ionic emulsifier..- 2. 0 1.5 to 3.0 parts. Water 85 Sufiicient for 45 to 55% solids.

Third preferred specific composition Another preferred specific composition comprises the following ingredients in parts by weight:

Preferred Permissible Ingredient quantity, quantity parts range Polystyrene emulsion 140 110 to 150 parts.

60 50 to 70 parts. 20 to 30 parts. 80 Sufficient for 45 to 55% solids.

Fourth specific composition Still another specific composition includes the following ingredients in parts by weight:

It will be seen that in the foregoing preferred examples the phthalate and phosphate plasticizers are mixed in a ratio from about 127 (Examples I and II) to about 1:3 (Example III).

In preparing the tackifier composition, the plasticizer and emulsifier ingredients are mixed and then added to water and thoroughly mixed in any suitable manner. After a thoroughly dispersed mixture has been obtained, the resin emulsion is added gradually and stirring continues until all of the resin has been thoroughly mixed. Desirably, the completed mixture should be aged for 48 hours or more and stirred from time to time. The composition is now ready for application to cheesecloth, preferably 24-20 threads per inch, or other suitable fibrous Webbing.

Before applying the tackifier composition to fabric to form tack cloths, the composition is again thoroughly stirred and then distributed to the cloth in any suitable manner to impregnate all fibers thereof. cheesecloth of the aforementioned type measuring 18 x 36 inches provides an excellent tack cloth when suificient tackifier composition is applied to leave a dried residual solids deposit in the cloth ranging between 10 and 16 grams. Since a square yard of typical commercial bleached 24 x 20 cheesecloth weighs about 22 grams, it will be apparent that this half square yard which held a dried residue of about 10 to 16 grams had taken on from about one to one and a half times its own weight of tacky material. The impregnated cloth is dried in warm air to drive oi the water content. Circulating air heated to 300 degrees F. is effective to dry the cloths in four to five minutes.

After the water content has been dissipated, the cloths may be cut and folded in a convenient size for packaging and shipping and laid directly against one another in any suitable number without need for individual wrappings or other special separators of any kind inasmuch as the product is free from stickiness and gumminess.

The tackifier composition is milk white in color but transparent when dry and imparts no color to the tack cloth product. Since bleached cheesecloth is white, the application of the composition thereto does not materially alter the natural cloth color. Accordingly, the collection of dust and other foreign particles by the cloth in use discolors the cloth and provides the user with a convenient visual indicator of the rate at which foreign matter is being collected. Furthermore, owing to the continual and marked characteristic of the composition to creep over and engulf adhering particles, the tackifier rejuvenates constantly, and this property is easily noted if a seem ingly unserviceable cloth is laid aside for a period of time and then inspected. Thus, the tack cloth seemingly unfit for further service because of adhering dirt will be found to have its cleaning effectiveness restored to a high degree if left at rest for a period of several hours.

While preferred embodiments of the present cornposition have been described hereinabove, it will be understood that minor variations in the composition can be made by those skilled in the art without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. An improved tack cloth for use in removing dust and foreign particles from surfaces without adhering to the hand of a user, said cloth consisting essentially of fibrous backing material having stably deposited thereon a composition formed of two normally liquid plasticizers, one being a phthalate ester and the other a phosphate ester plasticizer, intimately dispersed among resinous polymer particles of no larger than about 0.5 micron, said polymer being obtained by polymerization of at least one compound containing a polymerizable vinylidene group and which plasticizer-polymer particles are coalesced in larger masses and deposited on said material,

the total minimum weight of plasticizer being approximately equal to the total weight of polymer.

2. The article of the preceding claim 1 wherein said plasticizers are dispersed through the coalesced polymer masses adhering to polymer particles having a maximum size of about 0.2 micron.

3. The article of the preceding claim 1 wherein said fibrous backing material is a fabric sheet.

4. The article of the preceding claim 1 wherein said polymer comprises polyvinyl acetate.

5. The article of the preceding claim 1 wherein said polymer comprises polyvinyl acetate and said plasticizers are 2-ethyl hexyl diphenyl phosphate and butyl benzyl phthalate.

6. The article of the preceding claim 1 wherein said polymer comprises butadiene styrene copolymer.

7. The article of the preceding claim 1 wherein said polymer comprises polystyrene.

8. The article of the preceding claim 1 wherein said polymer comprises methyl methacrylate.

9. The article of the preceding claim 1 wherein said fibrous backing material is essentially a sheet of cheesecloth impregnated with a minimum dry weight of said composition about equal to the weight of said material.

10. The article of the preceding claim 1 wherein said fibrous backing material comprises excelsior.

11. The article of the preceding claim 1 wherein said fibrous backing material comprises resilient material.

12. The method for preparing an improved tack cloth having stably tacky and substantially non-adhesive prop tween about 7 /2 to 1, and 3 to 1, together with polymeric polyvinyl acetate having a major portion of its particles less than about 0.5 micron size, the total minimum weight of said phosphate and phthalate being approximately equal to the weight of said polyvinyl acetate, maintaining said aqueous emulsion for about 48 hours and then applying same to a fibrous backing material with substantially complete removal of aqueous component therefrom, thereby depositing coalesced composite plasticized-polymer particles on said backing material in a weight ratio of about 10 to 16 parts dry particles to about 11 parts backing material, said dry particles being no longer waterdispersible and having stably tacky properties.

13. The method of the preceding claim 12 wherein said fibrous backing material is bleached cheesecloth.

14. An improved tack cloth for use in removing dust and foreign particles from surfaces without adhering to the hand of a user, said cloth consisting essentially of fibrous backing material having stably deposited thereon a composition formed of two normally liquid plasticizers, one being a phthalate ester and the other a phosphate ester plasticizer, intimately dispersed among resinous polymer particles of no larger than about 0.5 micron, said polymer being obtained by copolymerization of vinyl acetate with another compound containing a polymerizable vinylidene group and which plasticizer-polymer particles are coalesced in larger masses and deposited on said material, the total minimum weight of plasticizer being approximately equal to the total weight of polymer.

References Cited by the Examiner UNITED STATES PATENTS 2,413,197 12/46 Smith et al. 26029.6 2,575,553 11/51 Kolvoort 26029.6 2,613,156 10/52 McGaffin et a1 26029.6 2,628,948 2/ 53 Kunze et al 26029.6 2,633,593 4/53 Wright et a1 15209 2,783,166 2/56 Deanin 117-122 2,955,962 10/60 Engdahl 117--122 2,961,419 11/60 Cohen et al. 26029.6 3,016,555 1/ 62 Penoyer 15-209 MURRAY TILLMAN, Primary Examiner.

DONALD ARNOLD, LEON J. BERCOVITZ,

Examiners. 

1. AN IMPROVED TACK CLOTH FOR USE IN REMOVING DUST AND FOREIGN PARTICLES FROM SURFACES WITHOUT ADHERING TO THE HAND OF A USER, SAID CLOTH CONSISTING ESSENTIALLY OF FIBROUS BACKING MATERIAL HAVING STABLY DEPOSITED THEREON A COMPOSITION FORMED OF TWO NORMALLY LIQUID PLASTICIZERS, ONE BEING A PHTHALATE ESTER AND THE OTHER A PHOSPHATE ESTER PLASTICIZER, INTIMATELY DISPERSED AMONG RESINOUS POLYMER PARTICLES OF NO LARGER THAN ABOUT 0.5 MICRON, SAID POLYMER BEING OBTAINED BY POLYMERIZATION OF AT LEAST ONE COMPOUND CONTAINING A POLYMERIZABLE VINYLIDENE GROUP AND WHICH PLASTICIZER-POLYMER PARTICLES ARE COALESCED IN LARGER MASSES AND DEPOSITED ON SAID MATERIAL, THE TOTAL MINIMUM WEIGHT OF PLASTICIZER BEING APPROXIMATELY EQUAL TO THE TOTAL WEIGHT OF POLYMER. 